1. Field of the Invention
The present invention relates to a splice protection heater for protecting a fusion spliced portion of an optical fiber by heat shrinking a protection sleeve covering the fusion spliced portion, a fusion splicer including the splice protection heater, and a fusion splicing method.
2. Description of the Background Arts
Fusion splicing of optical fibers is performed by heating and fusing abutting end portions of glass fibers that have been exposed by removing protective coatings on splicing ends of the optical fibers. Since a part of the fusion spliced optical fiber where the glass fiber has been exposed is mechanically weak, it is necessary to protect the part with a protection sleeve. The protection sleeve is usually configured by accommodating hot-melt adhesive resin and a tensile body (also referred to as a reinforcing rod) within a heat shrinkable tube that shrinks in the radial direction when heat is applied thereto (for example, refer to Japanese Patent Application Laid-Open No. 09-297243).
In general, when protecting a fusion spliced optical fiber, the fusion-spliced portion of the optical fiber is disposed in a housing part of a splice protection heater with a protective sleeve covering the portion. Next, the heating element is switched ON, and then later switched OFF after heating the protection sleeve for a predetermined time, whereupon the fusion-spliced portion is removed from the splice protection heater. The switch of the heating element is configured to be ON with a timing determined by an operator regardless of whether or not the fusion-spliced portion is in the splice protection heater.
However, a loss of time may be incurred, for example, if an operator forgets to turn the switch ON after having disposed a fusion-spliced portion in the splice protection heater. Furthermore, a fusion-spliced portion may be broken or damaged if an operator removes the unprotected optical fiber from the splice protection heater after a fixed time without becoming aware that he has not turned the switch ON. Moreover, a proper protection process may not be performed because of an insufficient actual heating time if the switch is turned ON before a fusion-spliced portion is disposed in the housing part of the splice protection heater. An operator may forget to manually switch the heating element ON or OFF regardless of the care taken and an ON/OFF timing of the switch may not be uniform.
Furthermore, batch fusion splicing of a plurality of optical fibers and batch protection processing of the plurality of optical fibers are known (for example, refer to Japanese Patent Application Laid-Open No. 02-72305). In this case, although respective fusion spliced portions are disposed in separate channels provided on the heating platform of the splice protection heater, the heating element is turned ON with a switch to thermally protect the plurality of fusion-spliced portions in a batch. This arrangement cannot be applied, therefore, if different types of protection sleeves that require different heating times for processing are used. In addition, once the switch of the heating element is turned ON, protection sleeves cannot be added until the thermal protection process ends.
In a general fusion splicing process, time required for the splicing operation is 10˜20 seconds, and time required for the protection operation is 40˜135 seconds. Therefore, even though the splicing operation is performed quickly, the thermal protection operation to the following fusion spliced fiber cannot be started and an idle time in a standby state is caused until the protection process of the preceding fusion spliced fiber has been completed. Although splicing operation can be performed parallel to the protection operation, the fusion-spliced portion as itself that has not yet been protected is extremely weak. Therefore, a situation where many fusion-spliced optical fibers waiting protection processing are accumulated may cause problems in which a fusion-spliced portion is broken, damaged or the like by an external force.